S. Carreira et al., STABILITY OF THE MESSENGER-RNA ENCODING SOME PANCREATIC HYDROLASES ISMODULATED BY DIETARY-PROTEIN INTAKE IN THE RAT, British Journal of Nutrition, 78(5), 1997, pp. 833-843
Wistar rats fed on either a high-protein or a protein-free diet were e
xamined to determine their pancreatic hydrolase mRNA stabilities in co
mparison with those of control animals receiving a standard diet. Acti
nomycin D was used to inhibit transcription and, after isolating the p
ancreatic RNA, the specific messengers were quantified by performing d
ot-blot hybridization with cDNA probes. In the rats fed on a high-prot
ein diet, only the half-lives of anionic trypsinogen I and elastase I(
EC 3.4.21.36) were affected. Interestingly, when rats mere fed on the
protein-free diet, most of the hydrolase mRNA half-lives showed change
s, except that corresponding to lipase. In these rats, the half-hfe va
lues of the mRNA coding for anionic trypsinogen I, chymotrypsinogen an
d procarboxypeptidase B increased, in sharp contrast with those of the
amylase and elastase I mRNA, which decreased. These results strongly
suggest that the mechanism whereby the biosynthesis of pancreatic hydr
olases is regulated, depending on the presence or absence of proteins
in the diet, is not unique and provide evidence that the stability of
mRNA encoding most, if not all, the hydrolases in pancreatic cells is
modulated by the dietary protein content.